Browsing by Subject "Yeast surface display"

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Open Access
Peptide based ligand discovery to prevent protein aggregation in neurodegenerative disease conditions
(2019-09) Beğli, Özge
Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease are cognitively and physically debilitating and progressive diseases due to the gradual and irreversible loss of discrete neuronal populations in the brain. In addition to millions of people worldwide suffering from them, the prevalence of the neurodegenerative diseases dramatically increases with the increasing lifespan of the population. Most of the current therapeutic strategies either target toxic aggregates in neurons or support the healthy cells in diseased region. However, these interventions provide only symptomatic relief and deceleration of disease progression. Besides, aggregation involves a locking phase in which irreversible transition of soluble monomeric and oligomeric molecules into insoluble fibrous structures occurs. During aggregation, fragmentation of mature fibrils leads to the formation of new oligomeric structures possessing seeding activity. The seeds behaving as a nucleation unit trigger other structures to join the accumulated proteins. Synthetic biology is an emerging field that suggests therapeutic solutions for several diseases. Development of synthetic proteins such as artificial transcription factors and improved antibodies, artificial cell transplants with controlled secretion, designed inhibitory RNA molecules and antisense oligonucleotides, gene circuits and logic gates, synthetic viruses as an advanced delivery system and genome editing technologies using programmable nucleases are revolutionary approaches for the diagnosis and treatment of diseases. With the utilization of a variety of advanced tools, synthetic biology is extremely promising to treat neurodegenerative disorders too. In this study, biotechnological approaches and tools such as gene cloning, yeast surface display and phage display library have been used to target neurodegenerative proteins before aggregation takes place. Neurodegenerative proteins were cloned into a plasmid DNA within bacteria and displayed on the surface of Saccharomyces cerevisiae cells. A phage display library has been screened against those neurodegenerative proteins and binding peptides of these proteins have been selected following recursive rounds of binding and washing steps. Peptides that bind to neurodegenerative proteins with high affinity possess the potential to block them and prevent the initiation of aggregation. Beside to the promising results of neuroprotective and neurorestorative interventions, this strategy can provide prevention of aggregation which is the underlying cause of neurodegeneration.
Open Access
Synergistic screening of peptide-based biotechnological drug candidates for neurodegenerative diseases using yeast display and phage display
(American Chemical Society, 2023-10-04) Özçelik, Cemile Elif; Beğli, Özge; Hınçer, Ahmet; Ahan, Recep Erdem; Kesici, M. S.; Oğuz, Oğuzhan; Kasırga, Talip Serkan; Özçubukçu, S.; Şeker, Urartu Özgür Şafak
Peptide therapeutics are robust and promising molecules for treating diverse disease conditions. These molecules can be developed from naturally occurring or mimicking native peptides, through rational design and peptide libraries. We developed a new platform for the rapid screening of the peptide therapeutics for disease targets. In the course of the study, we aimed to employ our platform to screen a new generation of peptide therapeutic candidates against aggregation-prone protein targets. Two peptide drug candidates were screened for protein aggregation-prone diseases, namely, Parkinson’s and Alzheimer’s diseases. Currently, there are several therapeutic applications that are only effective in masking or slowing down symptom development. Nonetheless, different approaches are being developed for inhibiting amyloid aggregation in the secondary nucleation phase, which is critical for amyloid fibril formation. Instead of targeting secondary nucleated protein structures, we tried to inhibit the aggregation of monomeric amyloid units as a novel approach for halting the disease condition. To achieve this, we combined yeast surface display and phage display library platforms. We expressed α-synuclein, amyloid β40, and amyloid β42 on the yeast surface, and we selected peptides by using phage display library. After iterative biopanning cycles optimized for yeast cells, several peptides were selected for interaction studies. All of the peptides have been used for in vitro characterization methods, which are quartz crystal microbalance-dissipation (QCM-D) measurement, atomic force microscopy (AFM) imaging, dot-blotting, and ThT assay, and some of them have yielded promising results in blocking fibrillization. The rest of the peptides, although, interacted with amyloid units which made them usable as a sensor molecule candidate. Therefore, peptides selected by yeast surface display and phage display library combination are good choice for diverse disease-prone molecule inhibition, particularly those inhibiting fibrillization. Additionally, these selected peptides can be used as drugs and sensors to detect diseases quickly and halt disease progression.